Showing papers on "Symmetry (physics) published in 2004"
TL;DR: In this article, all 1/2 BPS excitations of AdS × S configurations in both type-IIB string theory and M-theory are considered and a large class of explicit solutions are presented.
Abstract: We consider all 1/2 BPS excitations of AdS × S configurations in both type-IIB string theory and M-theory. In the dual field theories these excitations are described by free fermions. Configurations which are dual to arbitrary droplets of free fermions in phase space correspond to smooth geometries with no horizons. In fact, the ten dimensional geometry contains a special two dimensional plane which can be identified with the phase space of the free fermion system. The topology of the resulting geometries depends only on the topology of the collection of droplets on this plane. These solutions also give a very explicit realization of the geometric transitions between branes and fluxes. We also describe all 1/2 BPS excitations of plane wave geometries. The problem of finding the explicit geometries is reduced to solving a Laplace (or Toda) equation with simple boundary conditions. We present a large class of explicit solutions. In addition, we are led to a rather general class of AdS5 compactifications of M-theory preserving = 2 superconformal symmetry. We also find smooth geometries that correspond to various vacua of the maximally supersymmetric mass-deformed M2 brane theory. Finally, we present a smooth 1/2 BPS solution of seven dimensional gauged supergravity corresponding to a condensate of one of the charged scalars.
1,120 citations
TL;DR: By invoking the twisted Poincare symmetry of the algebra of functions on a Minkowski space-time, this paper showed that the non-commutative space time with the commutation relations [ x μ, x ν ] = i θ μ ν, where θμ ν is a constant real antisymmetric matrix, can be interpreted in a Lorentz-invariant way.
655 citations
TL;DR: A very simple one-dimensional swimmer consisting of three spheres that are linked by rigid rods whose lengths can change between two values can be used in constructing molecular-sized machines.
Abstract: We propose a very simple one-dimensional swimmer consisting of three spheres that are linked by rigid rods whose lengths can change between two values. With a periodic motion in a nonreciprocal fashion, which breaks the time-reversal symmetry as well as the translational symmetry, we show that the model device can swim at low Reynolds number. This model system could be used in constructing molecular-sized machines.
519 citations
TL;DR: The Stueckelberg mechanism was introduced in this paper to reveal a symmetry of a gauge-fixed theory, which led to applications in many areas not anticipated by the author, such as strings.
Abstract: In 1938, Stueckelberg introduced a scalar field which makes an Abelian gauge theory massive but preserves gauge invariance. The Stueckelberg mechanism is the introduction of new fields to reveal a symmetry of a gauge--fixed theory. We first review the Stueckelberg mechanism in the massive Abelian gauge theory. We then extend this idea to the standard model, stueckelberging the hypercharge U(1) and thus giving a mass to the physical photon. This introduces an infrared regulator for the photon in the standard electroweak theory, along with a modification of the weak mixing angle accompanied by a plethora of new effects. Notably, neutrinos couple to the photon and charged leptons have also a pseudo-vector coupling. Finally, we review the historical influence of Stueckelberg's 1938 idea, which led to applications in many areas not anticipated by the author, such as strings. We describe the numerous proposals to generalize the Stueckelberg trick to the non-Abelian case with the aim to find alternatives to the standard model. Nevertheless, the Higgs mechanism in spontaneous symmetry breaking remains the only presently known way to give masses to non-Abelian vector fields in a renormalizable and unitary theory.
419 citations
TL;DR: In this paper, the role of triplets of totally symmetric tensors and spinor-tensors and their generalizations to cases with mixed symmetry and to (A)dS backgrounds is discussed.
326 citations
TL;DR: The superconformal origin of the Fayet-Iliopoulos (FI) terms is clarified in this article, where the authors introduce the general N = 1 gauge theory superconsformally coupled to supergravity, which has local SU(2,2|1) symmetry and no dimensional parameters.
Abstract: We introduce the general N = 1 gauge theory superconformally coupled to supergravity. The theory has local SU(2,2|1) symmetry and no dimensional parameters. The superconformal origin of the Fayet-Iliopoulos (FI) terms is clarified. The phase of this theory with spontaneously broken conformal symmetry gives various formulations of N = 1 supergravity interacting with matter, depending on the choice of the R-symmetry fixing. We have found that the locally superconformal theory is useful for describing the physics of the early universe with a conformally flat FRW metric. Few applications of superconformal theory to cosmology include the study of (a) particle production after inflation, particularly the nonconformal helicity-±½ states of gravitino, (b) the super-Higgs effect in cosmology and the derivation of the equations for the gravitino interacting with any number of chiral and vector multiplets in the gravitational background with varying scalar fields, (c) the weak-coupling limit of supergravity MP→∞ and gravitino-goldstino equivalence. This explains why gravitino production in the early universe is not suppressed in the limit of weak gravitational coupling. We discuss the possible existence of an unbroken phase of the superconformal theories, interpreted as a strong-coupling limit of supergravity MP→0.
222 citations
TL;DR: For large classes of vorticities, this article showed that a steady periodic gravity water wave with a monotonic profile between crests and troughs must be symmetric.
Abstract: For large classes of vorticities we prove that a steady periodic gravity water wave with a monotonic profile between crests and troughs must be symmetric. The analysis uses sharp maximum principles for elliptic partial differential equations.
201 citations
196 citations
TL;DR: In this article, the influence of spin-orbit coupling on the spin susceptibility of superconductors was discussed, with a particular emphasis on the recently discovered heavy Fermion superconductor CePt3Si.
Abstract: In materials without spatial inversion symmetry, the spin degeneracy of the conduction electrons can be lifted by an antisymmetric spin–orbit coupling. We discuss the influence of this spin–orbit coupling on the spin susceptibility of such superconductors, with a particular emphasis on the recently discovered heavy Fermion superconductor CePt3Si. We find that, for this compound (with tetragonal crystal symmetry) irrespective of the pairing symmetry, the stable superconducting phases would give a very weak change of the spin susceptibility for fields along the c-axis and an intermediate reduction for fields in the basal plane. We also comment on the consequences for the paramagnetic limiting in this material.
177 citations
TL;DR: In this paper, the authors apply Krein space methods to PT-symmetric problems to obtain conditions for the spectrum to be real and estimates of the number of non-real spectral points.
Abstract: In this note we apply Krein space methods to PT-symmetric problems to obtain conditions for the spectrum to be real and estimates of the number of non-real spectral points
160 citations
TL;DR: In this article, the effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei were investigated using an isospin and momentum dependent transport model.
TL;DR: In this article, the authors considered solutions with conformal symmetry of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario, and they considered the behavior of the angular velocity of a test particle moving in a stable circular orbit.
Abstract: We consider solutions with conformal symmetry of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario. By assuming that the vector field generating the symmetry is nonstatic, the general solution of the field equations on the brane can be obtained in an exact parametric form, with the conformal factor taken as parameter. As a physical application of the obtained solutions we consider the behavior of the angular velocity of a test particle moving in a stable circular orbit. In this case the tangential velocity can be expressed as a function of the conformal factor and some integration constants only. For a specific range of integration constants, the tangential velocity of the test particle tends, in the limit of large radial distances, to a constant value. This behavior is specific to galactic rotation curves and is explained usually by invoking the hypothesis of dark matter. The limiting value of the angular velocity of the test particle can be obtained as a function of the baryonic mass and radius of the galaxy. The behavior of the dark radiation and dark pressure terms is also considered in detail, and it is shown that they can be expressed in terms of the rotational velocity of a test particle. Hence all the predictions of the present model can be tested observationally. Therefore the existence of the nonlocal effects, generated by the free gravitational field of the bulk in a conformally symmetric brane, may provide an explanation for the dynamics of the neutral hydrogen clouds at large distances from the galactic center.
TL;DR: In this article, an integrable structure for weakly coupled superconformal Yang-Mills theories is discussed, and certain equivalences for the Yangian algebra are described.
Abstract: We will discuss an integrable structure for weakly coupled superconformal Yang-Mills theories, describe certain equivalences for the Yangian algebra, and fill a technical gap in our previous study of this subject.
TL;DR: In this article, the authors consider all 1/2 BPS excitations of $AdS \times S$ configurations in both type IIB string theory and M-theory and present a large class of explicit solutions.
Abstract: We consider all 1/2 BPS excitations of $AdS \times S$ configurations in both type IIB string theory and M-theory. In the dual field theories these excitations are described by free fermions. Configurations which are dual to arbitrary droplets of free fermions in phase space correspond to smooth geometries with no horizons. In fact, the ten dimensional geometry contains a special two dimensional plane which can be identified with the phase space of the free fermion system. The topology of the resulting geometries depends only on the topology of the collection of droplets on this plane. These solutions also give a very explicit realization of the geometric transitions between branes and fluxes. We also describe all 1/2 BPS excitations of plane wave geometries. The problem of finding the explicit geometries is reduced to solving a Laplace (or Toda) equation with simple boundary conditions. We present a large class of explicit solutions. In addition, we are led to a rather general class of $AdS_5$ compactifications of M-theory preserving ${\cal N} =2$ superconformal symmetry. We also find smooth geometries that correspond to various vacua of the maximally supersymmetric mass-deformed M2 brane theory. Finally, we present a smooth 1/2 BPS solution of seven dimensional gauged supergravity corresponding to a condensate of one of the charged scalars.
TL;DR: A set of symmetry relations with respect to bias voltage and magnetic field for the nonlinear conductance of two-terminal electric conductors are proposed and experimentally confirmed using phase-coherent, semiconductor quantum dots.
Abstract: The well-established symmetry relations for linear transport phenomena cannot, in general, be applied in the nonlinear regime. Here we propose a set of symmetry relations with respect to bias voltage and magnetic field for the nonlinear conductance of two-terminal electric conductors. We experimentally confirm these relations using phase-coherent, semiconductor quantum dots.
TL;DR: In this article, a frame-like covariant Lagrangian formulation of higher spin massless fields propagating on the AdS d background is proposed, where higher spin fields are described in terms of gauge p -forms which carry tangent indices representing certain traceless tensor or gamma transversal spinor-tensor representations.
TL;DR: In this paper, a model for the lepton sector based on the seesaw mechanism and on a D4 family symmetry was proposed, which predicts the mixing angle �13 to vanish.
Abstract: We discuss a model for the lepton sector based on the seesaw mechanism and on a D4 family symmetry. The model predicts the mixing angle �13 to vanish. The solar mixing angle �12 is free—it will in general be large if one does not invoke finetuning. The model has an enlarged scalar sector with three Higgs doublets, together with (�)
TL;DR: Measurements show that quasi-particles with fractional charge e* = e/3 localize in space to submicrometer dimensions, where e is the electron charge.
Abstract: An outstanding question pertaining to the microscopic properties of the fractional quantum Hall effect is understanding the nature of the particles that participate in the localization but that do not contribute to electronic transport. By using a scanning single electron transistor, we imaged the individual localized states in the fractional quantum Hall regime and determined the charge of the localizing particles. Highlighting the symmetry between filling factors 1/3 and 2/3, our measurements show that quasi-particles with fractional charge e* = e/3 localize in space to submicrometer dimensions, where e is the electron charge.
TL;DR: For a large class of vorticities, this article proved that a steady periodic deep-water wave must be symmetric if its profile is monotone between crests and troughs.
Abstract: For a large class of vorticities we prove that a steady periodic deep-water wave must be symmetric if its profile is monotone between crests and troughs.
TL;DR: In this article, the effects of the momentum dependence of the symmetry potential in nuclear reactions induced by neutron-rich nuclei at Rare Isotope Accelerator (RIA) energies are studied using an isospin and momentum-dependent transport model.
Abstract: Effects of the momentum dependence of the symmetry potential in nuclear reactions induced by neutron-rich nuclei at Rare Isotope Accelerator (RIA) energies are studied using an isospin- and momentum-dependent transport model. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy ${E}_{sym}(\ensuremath{\rho})$ lead to significantly different predictions on several ${E}_{sym}(\ensuremath{\rho})$-sensitive experimental observables. The momentum dependence of the symmetry potential is thus critically important for investigating accurately the equation of state and novel properties of dense neutron-rich matter at RIA.
TL;DR: In this article, the phase space of the O(textit{N}) phantom model with O(emph{N} symmetry in exponential potential was studied and a lower bound on the equation of state for the existence of stable phantom dominated attractor phase was derived.
Abstract: In this paper, we study the phase space of phantom model with O(\emph{N}) symmetry in exponential potential. Different from the model without O(\emph{N}) symmetry, the introduction of the symmetry leads to a lower bound $w>-3$ on the equation of state for the existence of stable phantom dominated attractor phase. The reconstruction relation between the potential of O(\textit{N}) phantom system and red shift has been derived.
TL;DR: In this article, the theoretical significance of a high precision measurement of the neutrino mixing parameter θ13 was discussed and it was emphasized that it will provide crucial information about different ways to understand the origin of large atmospheric neutrinos mixing and move us closer towards determining the Neutrino mass matrix.
Abstract: Many experiments are being planned to measure the neutrino mixing parameter θ13 using reactor as well as accelerator neutrino beams. In this note, the theoretical significance of a high precision measurement of this parameter is discussed. It is emphasized that it will provide crucial information about different ways to understand the origin of large atmospheric neutrino mixing and move us closer towards determining the neutrino mass matrix. For instance if exact μτ symmetry in the neutrino mass matrix is assumed to be the reason for maximal νμ−ντ mixing, one gets θ13 = 0. Whether θ13 (Δm 2 ⊙/Δm 2 A )1/2 or θ13 Δm 2 ⊙/Δm 2 A can provide information about the way the μτ symmetry breaking manifests in the case of normal hierarchy. We also discuss the same question for inverted hierarchy as well as possible gauge theories with this symmetry.
TL;DR: In this paper, the symmetry breaking bifurcation of an asymmetric ground state and the exchange of dynamical stability from the symmetric branch to the asymmetric branch at the symmetry-breaking point was studied.
Abstract: Gross–Pitaevskii and nonlinear Hartree equations are equations of nonlinear Schrodinger type that play an important role in the theory of Bose–Einstein condensation. Recent results of Aschbacher et al.(3) demonstrate, for a class of 3-dimensional models, that for large boson number (squared L
2norm),
$$N$$
, the ground state does not have the symmetry properties of the ground state at small
$$N$$
. We present a detailed global study of the symmetry breaking bifurcation for a 1-dimensional model Gross–Pitaevskii equation, in which the external potential (boson trap) is an attractive double-well, consisting of two attractive Dirac delta functions concentrated at distinct points. Using dynamical systems methods, we present a geometric analysis of the symmetry breaking bifurcation of an asymmetric ground state and the exchange of dynamical stability from the symmetric branch to the asymmetric branch at the bifurcation point.
TL;DR: Modifications to the concept of an "antiparticle," induced by a breakdown of the CPT symmetry at a fundamental level, realized within an extended class of quantum gravity models, are discussed.
Abstract: We discuss modifications to the concept of an "antiparticle," induced by a breakdown of the CPT symmetry at a fundamental level, realized within an extended class of quantum gravity models. The resulting loss of particle-antiparticle identity in the neutral-meson system induces a breaking of the Einstein-Podolsky-Rosen correlation imposed by Bose statistics. This is parametrized by a complex parameter associated with the contamination by the "wrong symmetry" state. The physical consequences are studied, and novel observables of CPT violation in phi factories are proposed.
TL;DR: In this paper, the authors identify a class of models where the shift symmetry uniquely follows from the underlying mathematical structure of the theory, and show how the gauge coupling depends on the volume and the position of the branes.
Abstract: The main problem of inflation in string theory is finding the models with a flat potential, consistent with stabilization of the volume of the compactified space. This can be achieved in the theories where the potential has (an approximate) shift symmetry in the inflaton direction. We will identify a class of models where the shift symmetry uniquely follows from the underlying mathematical structure of the theory. It is related to the symmetry properties of the corresponding coset space and the period matrix of special geometry, which shows how the gauge coupling depends on the volume and the position of the branes. In particular, for type IIB string theory on K3xT^2/Z with D3 or D7 moduli belonging to vector multiplets, the shift symmetry is a part of SO(2,2+n) symmetry of the coset space [SU(1,1)/ U(1)]x[SO(2,2+n)/(SO(2)x SO(2+n)]. The absence of a prepotential, specific for the stringy version of supergravity, plays a prominent role in this construction, which may provide a viable mechanism for the accelerated expansion and inflation in the early universe.
TL;DR: Translational friction coefficients for cylinders of arbitrary axial ratios are calculated using Monte Carlo simulation and an approximate description of the hydrodynamic interaction and indicate that the approximate description is exact for ellipsoids and this result is generalized to include cylinders, which possess the same symmetry as ellipSOids.
Abstract: Translational friction coefficients for cylinders of arbitrary axial ratios (including disks) are calculated using Monte Carlo simulation and an approximate description of the hydrodynamic interaction. The calculations indicate that the approximate description is exact for ellipsoids and this result is generalized to include cylinders, which possess the same symmetry as ellipsoids. From the result an approximate formula for the translational friction coefficient of cylinders is calculated which is compared to results from other sources.
TL;DR: The apparent persistence of symmetry in the face of strong symmetry-breaking interactions is examined in a many-boson model that continues to exhibit the characteristics of its closest symmetry limit for all but a relatively narrow transition region that becomes progressively narrower as the boson number increases.
Abstract: The apparent persistence of symmetry in the face of strong symmetry-breaking interactions is examined in a many-boson model. The model exhibits a transition between two phases associated with U(5) and O(6) symmetries, respectively, as the value of a control parameter progresses from 0 to 1. The remarkable fact is that, in spite of strong mixing of the symmetries for intermediate values of the control parameter, the model continues to exhibit the characteristics of its closest symmetry limit for all but a relatively narrow transition region that becomes progressively narrower as the boson number increases. This phenomenon is explained in terms of quasidynamical symmetry.
TL;DR: In this article, the general applicability of the overall permutation symmetry condition originally proposed by Kleinman in describing the non-resonant nonlinear optical properties of the overwhelming majority of practical materials and systems is examined.
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TL;DR: In this article, the generalized gravity with global instead of local Lorentz symmetry was explored in first order derivative expansion. But it was only very partially tested by present observations, and the second possible new coupling is severely restricted by present solar system observations.
Abstract: We investigate a possible unified theory of all interactions which is based only on fundamental spinor fields. The vielbein and metric arise as composite objects. The effective quantum gravitational theory can lead to a modification of Einstein's equations due to the lack of local Lorentz symmetry. We explore the generalized gravity with global instead of local Lorentz symmetry in first order of a systematic derivative expansion. At this level diffeomorphisms and global Lorentz symmetry allow for two new invariants in the gravitational effective action. The one which arises in the one loop approximation to spinor gravity is consistent with all present tests of general relativity and cosmology. This shows that local Lorentz symmetry is tested only very partially by present observations. In contrast, the second possible new coupling is severely restricted by present solar system observations.
TL;DR: In this article, the empirical significance of continuous symmetries of physics is discussed. But the interpretation of the examples is mistaken, and it is not clear how to interpret the examples.
Abstract: In a recent paper in the British Journal for the Philosophy of Science, Kosso discussed the observational status of continuous symmetries of physics. While we are in broad agreement with his approach, we disagree with his analysis. In the discussion of the status of gauge symmetry, a set of examples offered by ’t Hooft has influenced several philosophers, including Kosso; in all cases the interpretation of the examples is mistaken. In this paper we present our preferred approach to the empirical significance of symmetries, re-analysing the cases of gauge symmetry and general covariance.